Offset-printing method for three-dimensional printed memory with multiple bits-per-cell

ABSTRACT

The present invention discloses an offset-printing method for a three-dimensional printed memory with multiple bits-per-cell. The mask-patterns for different bits-in-a-cell are merged onto a multi-region data-mask. At different printing steps, a wafer is offset by different values with respect to the data-mask. Accordingly, data-patterns from a same data-mask are printed into different bits-in-a-cell.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application “Three-DimensionalOffset-Printed Memory”, application Ser. No. 14/876,908, filed Oct. 7,2015, which is a continuation of application “Three-DimensionalOffset-Printed Memory”, application Ser. No. 13/599,085, filed Aug. 30,2012, which relates to a provisional application, “Three-DimensionalOffset-Printed Memory”, application Ser. No. 61/529,920, filed Sep. 1,2011.

BACKGROUND

1. Technical Field of the Invention

The present invention relates to the field of integrated circuit, andmore particularly to mask-programmed read-only memory (mask-ROM).

2. Prior Arts

Three-dimensional mask-programmed read-only memory (3D-MPROM) has thepotential to replace DVD and Blu-Ray Discs. It is ideal for masspublication. U.S. Pat. No. 5,835,396 discloses a 3D-MPROM. It is amonolithic semiconductor memory. As illustrated in FIG. 1, a typical3D-MPROM comprises a semiconductor substrate 0 and a 3-D stack 10stacked above. The 3-D stack 10 comprises M(M≥2) vertically stackedmemory levels (e.g. 10A, 10B). Each memory level (e.g. 10A) comprises aplurality of upper address lines (e.g. 2 a), lower address lines (e.g. 1a) and memory cells (e.g. 5 aa). Each memory cell stores n (n≥1) bits.Memory levels (e.g. 10A, 10B) are coupled to the substrate 0 throughcontact vias (e.g. 1 av, 1 av′). The substrate circuit 0X in thesubstrate 0 comprises a peripheral circuit for the 3-D stack 10.Hereinafter, xMxn 3D-MPROM denotes a 3D-MPROM comprising M memory levelswith n bits-per-cell (bpc).

3D-MPROM is a diode-based cross-point memory. Each memory cell (e.g. 5aa) typically comprises a diode 3 d. The diode 3 d can be broadlyinterpreted as any device whose electrical resistance at the readvoltage is lower than that when the applied voltage has a magnitudesmaller than or polarity opposite to that of the read voltage. Eachmemory level (e.g. 10A) further comprises at least a data-coding layer(e.g. 6A). The pattern in the data-coding layer is a data-pattern and itrepresents the digital data stored in the data-coding layer. In thisfigure, the data-coding layer 6A is a blocking dielectric 3 b, whichblocks the current flow between the upper and lower address lines.Absence or existence of a data-opening (e.g. 6 ca) in the blockingdielectric 3 b indicates the state of a memory cell (e.g. 5 ca).

In prior arts, data-patterns for different memory levels are transferredfrom separate data-masks. Pattern-transfer is also referred to as“print”, transfers a data pattern from a data-mask to a data-codinglayer. Hereinafter, “mask” can be broadly interpreted as any apparatusthat carries the source image of the data to be printed. FIGS. 2A-2Billustrate two prior-art data-masks 4A, 4B. Each data-mask (e.g. 4A) iscomprised of an array of mask cells “aa”-“bd”. The mask-pattern (clearor dark) at each mask cell determines the existence or absence of adata-opening at the corresponding memory cell. For example, themask-opening 4 ca on the data-mask 4A leads to a data-opening 6 ca atcell 5 ca of the memory level 10A; the mask-openings 4′aa, 4′da on thedata-mask 4B lead to data-openings 6′aa, 6′da at cells 5′aa, 5′da of thememory level 10B.

To further increase storage density, 3D-MPROM can store n (n>1)bits-per-cell (bpc). U.S. patent application Ser. No. 12/785,621discloses a large-bpc 3D-MPROM. As illustrated in FIG. 3, each memorycell (e.g. 5 aa) stores two bits: Bit-1 and Bit-2. Bit-1 is physicallyimplemented by an extra implant, while Bit-2 is physically implementedby a resistive layer 3 r. Hereinafter, j-th bit-in-a-cell denotes thej-th bit stored in an n-bpc cell (n≥j). For example, the 1^(st)bit-in-a-cell in a 2-bpc cell is Bit-1; the 2^(nd) bit-in-a-cell in a2-bpc cell is Bit-2.

In prior arts, the data-patterns for different bits-in-a-cell (e.g.Bit-1, Bit-2) are printed from separate data-masks. FIGS. 4A-4Billustrate two prior-art data-masks 4C, 4D. Each data-mask (e.g. 4C) iscomprised of an array of mask cells “aa”-“bd”. The mask-pattern (clearor dark) at each mask cell determines the existence or absence of theextra implant or the resistive layer at the corresponding memory cell.For example, the mask-opening 4 xa* on the data-mask 4C leads to theextra-implanted layer 3 i at cells 5 ca, 5 da; the mask-openings 4′ba*,4′da* on the data-mask 4D lead to the removal of the resistive layer 3 rat cells 5 ba, 5 da.

Prior arts generally require M×n data-masks for an xMxn 3D-MPROM,because each memory level and each bit-in-a-cell need a separatedata-mask. At 22 nm node, each data-mask costs ˜$250 k (hereinafter,k=1,000). Accordingly, the data-mask set of an x8x2 3D-MPROM, including16 (=8×2) data-masks, will cost ˜$4 million. This high data-mask costwill hinder widespread applications of the 3D-MPROM. To lower thedata-mask cost, the present invention discloses a three-dimensionaloffset-printed memory (3D-oP).

OBJECTS AND ADVANTAGES

It is a principle object of the present invention to provide a 3D-MPROMwith a lower data-mask cost.

It is a further object of the present invention to provide a method toreduce the total number of data-masks of the 3D-MPROM.

In accordance with these and other objects of the present invention, athree-dimensional offset-printed memory (3D-oP) is disclosed.

SUMMARY OF THE INVENTION

The present invention discloses a three-dimensional offset-printedmemory (3D-oP). 3D-oP is an improved 3D-MPROM. It records data with anoffset-printing means. To realize offset-printing, the mask-patterns fora plurality of memory levels and/or bits-in-a-cell are merged onto amulti-region data-mask. At different printing steps, the wafer is offsetby different values with respect to the multi-region data-mask.Accordingly, data-patterns are printed into data-coding layers fordifferent memory levels/bits-in-a-cell from the same data-mask.Offset-printing lowers the total data-mask count and therefore, lowersthe total data-mask cost.

In a 3D-oP batch, all dice are printed from the same data-masks.Although different dice may have different data-array sequence, all dicehave a same data-array set. Here, a data-array is an array of digitalvalues represented by a data-coding layer at each cell location; thedata-array sequence is an ordered list of all data-arrays in a 3D-oPdie, e.g. from the one closet to the substrate to the one farthest fromthe substrate; and a data-array set is a collection of all data-arraysin a 3D-oP die.

To make the difference in the data-array sequence transparent to users,3D-oP preferably comprises a configurable-input/output (I/O) means. Itchanges inputs/outputs according to the data-array sequence of the 3D-oPdie. Compared with a reference 3D-oP die, if the data-array sequence fortwo memory levels in a 3D-oP die of interest is reversed, theprogrammable-I/O changes at least a portion of its input address; if thedata-array sequence for two bits-in-a-cell in this 3D-oP die isreversed, the programmable-I/O changes the bit-order of at least aportion of its output.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a x2x1 3D-MPROM along the cut-lineAA′ of FIGS. 2A-2B;

FIGS. 2A-2B disclose two data-masks for the x2x1 3D-MPROM in prior arts;

FIG. 3 is a cross-sectional view of a x1x2 3D-MPROM along the cut-lineBB′ of FIGS. 4A-4B;

FIGS. 4A-4B disclose two data-masks for the x1x2 3D-MPROM in prior arts;

FIGS. 5A-5B illustrate the printing steps used in a preferredoffset-printing means;

FIG. 6 discloses an exemplary multi-region data-mask;

FIGS. 7A-7B disclose the data-arrays m(1), m(2) represented by the twodata-mask regions on the multi-region data-mask;

FIGS. 8A-8B are the cross-sectional views of two 3D-oP dice 18 a, 1 8 bfrom a preferred x2x1 3D-oP batch;

FIGS. 9A-9B disclose two data-arrays p_(18a)[1], p₁₉₂[2] for the twomemory levels 16A, 16B of the 3D-oP die 18 a;

FIGS. 10A-10B are the cross-sectional views of two dice 18 c, 18 d froma preferred x1x2 3D-oP batch;

FIGS. 11A-11B disclose two data-arrays p_(18c)[1,1], p_(18c)[1,2] forBit-1, Bit-2 of the die 18 c;

FIG. 12 is a circuit block diagram of a preferred 3D-oP;

FIG. 13A is a circuit block diagram for the preferred x2x1 3D-oP; FIG.13B is a circuit block diagram for the preferred x1x2 3D-oP;

FIG. 14 is a cross-sectional view of a preferred x2x2 3D-oP;

FIG. 15 illustrates a multi-region data-mask for the preferred x2x23D-oP and all dice in an exposure field;

FIG. 16 is a table listing each data-array in each die after eachprinting step for the preferred x2x2 3D-oP;

FIG. 17 is a circuit block diagram of the preferred x2x2 3D-oP;

FIG. 18 is a cross-sectional view of a preferred x3x3x1 3D²-oP;

FIG. 19 is a circuit block diagram of the preferred 3D²-oP;

FIG. 20 illustrates a multi-region data-mask for the preferred 3D²-oPand all dice in an exposure field;

FIG. 21 is a table listing each data-array in each die after eachprinting step for the preferred 3D²-oP;

FIG. 22 is a table listing three types of packages in a 3D²-oP batch.

It should be noted that all the drawings are schematic and not drawn toscale. Relative dimensions and proportions of parts of the devicestructures in the figures have been shown exaggerated or reduced in sizefor the sake of clarity and convenience in the drawings. The samereference symbols are generally used to refer to corresponding orsimilar features in the different embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Those of ordinary skills in the art will realize that the followingdescription of the present invention is illustrative only and is notintended to be in any way limiting. Other embodiments of the inventionwill readily suggest themselves to such skilled persons from anexamination of the within disclosure.

In order to reduce the total number of data-masks, the present inventiondiscloses a three-dimensional offset-printed memory (3D-oP). It recordsdata with an offset-printing means. Offset-printing is a printing means.Major printing means includes photo-lithography and imprint-lithography(referring to the co-pending U.S. Pat. App. 61/529,919,“Three-Dimensional Printed Memory”): photo-lithography uses data-masksto print data, whereas imprint-lithography uses data-templates (alsoreferred to as master, stamp, or mold) to print data.

Referring now to FIGS. 5A-5B, an overview of the offset-printing meansis disclosed. It uses a multi-region data-mask 8. In this example, thismulti-region data-mask 8 comprises the mask-patterns for two differentmemory levels 16A, 16B. They are located in the data-mask regions 8 a, 8b, respectively.

The preferred offset-printing means comprises two printing steps. At the1^(st) printing step (FIG. 5A, i.e. lithography A to code the firstmemory level 16A), the origin O_(18a) of the die 18 a is initiallyaligned to the origin O_(M) of the data-mask region 8 a. During exposureE_(1a), the data-mask regions 8 a is printed to the data-coding layer 6Afor the memory level 16A of the dice 18 a, while the data-mask regions 8b is printed to the data-coding layer 6A for the memory level 16A of thedice 18 b.

At the 2^(nd) printing step (FIG. 5B, i.e. lithography B to code thesecond memory level 16B), the alignment position of the wafer 9 isoffset by a value of Δ_(y) from its alignment position at the 1^(st)printing step. Let d_(y) be the displacement between the dice 18 a and18 b. If Δ_(y)=d_(y), the origin O_(18b) of the die 18 b is initiallyaligned to origin O_(M). During exposure E_(2a), the data-mask region 8a is printed to the data-coding layer 6B for the memory level 16B of thedie 18 b.

During the next exposure E_(2b), as long as the stepping distance D_(y)is twice the displacement d_(y) between adjacent dice, the data-maskregion 8 b will be printed to the data-coding layer 6B for the memorylevel 16B of the die 18 a. Finally, on the finished wafer 9, in the die18 a, the data-mask regions 8 a, 8 b are printed to the data-codinglayers 6A, 6B for the memory levels 16A, 16B, respectively; while in thedie 18 b, they are printed to the data-coding layers 6B, 6A for thememory levels 16B, 16A, respectively.

FIG. 6 discloses more details on an exemplary multi-region data-mask 8.Each of its data-mask regions 8 a, 8 b is comprised of an array of maskcells “aa”-“bd”. In the data-mask region 8 a, the clear mask-patterns atthe mask cells “ca”, “bb”, “ab” form mask-openings 8 ca, 8 xb. In thedata-mask region 8 b, the clear mask-patterns at the mask cells “aa”,“da”, “bb” form mask-openings 8 aa, 8 da, 8 bb. If the followingconvention is used: the dark mask-pattern represents ‘0’ and the clearmask-pattern represents ‘1’, the digital values represented by each maskcell in the data-mask region 8 a form a data-array m(1) (FIG. 7A), whilethe digital values represented by each mask cell in the data-mask region8 b form a data-array m(2) (FIG. 7B).

Referring now to FIGS. 8A-8B, two dice 18 a, 18 b from a preferred x2x13D-oP batch are disclosed. In a 3D-oP batch, all dice are manufacturedwith the same mask set, and all dice have the same 3-D frame. Here, a3-D frame comprises all address lines in the 3-D stack, but nodata-coding layer. In this example, the data for both dice 18 a and 18 bare printed from the same data-mask 8. FIG. 8A discloses the x2x1 3-Dstack 16 a of the die 18 a. The data-coding layer 6A of the memory level16A is printed from the data-mask region 8 a, while the data-codinglayer 6B of the memory level 16B is printed from the data-mask region 8b. Here, the following convention is used: absence of a data-openingrepresents ‘0’ and existence of a data-opening represents ‘1’.Accordingly, in the 3D-oP die 18 a, the digital values stored in allmemory cells in the memory level 16A form a data-array p_(18a)[1] ofFIG. 9A; the digital values stored in all memory cells in the memorylevel 16B form a data-array p_(18a)[2] of FIG. 9B. It can observed thatthe data-array p_(18a)[1] is same as the mask data-array m(1) of FIG.7A, i.e. p_(18a)[1]=m(1); and, the data-array p_(18a)[2] is same as themask data-array m(2) of FIG. 7B, i.e. p_(18a)[2]=m(2).

On the other hand, FIG. 8B discloses the x2x1 3-D stack 16 b of the die18 b. The data-coding layer 6A of the memory level 16A is printed fromthe data-mask region 8 b, while the data-coding layer 6B of the memorylevel 16B is printed from the data-mask region 8 a. Similarly, for die18 b, p_(18a)[1]=m(2), p_(18b)[2]=m(1).

In a 3D-oP batch, an ordered list (e.g. from the one closet to thesubstrate to the one farthest from the substrate) of all data-arrays(including the arrays for all memory levels and all bits-in-a-cell) ineach 3D-oP die forms a data-array sequence S. A collection of thesedata-arrays forms a data-array set. By definition, the value of a set isonly related to its elements, not the order of these elements. For thedice 18 a, 18 b of FIGS. 8A-8B, their data-array sequence can beexpressed as:{S _(18a) }={p _(18a)[1], p _(18a)[2]}={m(1), m(2)};{S _(18b) }={p _(18b)[1], p _(18b)[2]}={m(2), m(1)};with {S_(18a)}={S_(18b)}, but S_(18a)≠S_(18b).It can be observed that, the data-array set of the die 18 a is same asthat of the die 18 b, while the data-array sequence of the die 18 a is areverse of that of the die 18 b. To access the same data, differentmemory level needs to be accessed in the die 18 b than that in the die18 a.

Referring now to FIGS. 10A-10B, offset-printing can also be applied tothe 3D-MPROM with n bits-per-cell (bpc). Similarly, the mask-patternsfor two different bits-in-a-cell are merged onto a multi-regiondata-mask. At different printing steps, the wafer is offset by differentvalues with respect to the multi-region data-mask. Accordingly, variousdata-patterns from the same data-mask are printed into data-codinglayers for different bits-in-a-cell. Two x1x2 3D-oP dice 18 c, 18 d froma preferred 3D-oP batch are illustrated in FIG. 10A-10B.

FIG. 10A discloses an x1x2 3-D stack 16 c of die 18 c. Each memory cell(e.g. 5 aa) in the memory level 16A stores two bits: Bit-1 and Bit-2.Bit-1 is represented by a first data-coding layer 6C, i.e. anextra-implanted layer 3 i; Bit-2 is represented by a second data-codinglayer 6D, i.e. a resistive layer 3 r. The data-coding layer 6C of Bit-1is printed from the data-mask region 8 a, while the data-coding layer 6Dof Bit-2 is printed from the data-mask region 8 b. Here, the followingconvention is used: existence of an extra implant represents ‘0’ andabsence of an extra implant represents ‘1’; existence of the resistivelayer represents ‘0’ and absence of the resistive layer represents ‘1’.Accordingly, in the first memory level 16C of the 3D-oP die 18 c, thedigital values stored by Bit-1 form the data-array p_(18c)[1,1] of FIG.11A; the digital values stored by Bit-2 form the data-array p_(18c)[1,2]of FIG. 11B. Here, p[i,j] means the data-array for j^(th)-bit-in-a-cellon the i^(st) memory level of the die 18 c. It can be observed that, thedata-array p_(18c)[1,1] is opposite to the data-array m(1) of FIG. 7A,i.e. p_(18c)[1,1]=−m(1); the data-array p_(18c)[1,2] is equal to thedata-array m(2) of FIG. 7B, i.e. p_(18c)[1,2]=−m(2). Here, the symbol“−” means ‘0’, ‘1’ are interchanged. Because the digital values in adata-array could change with definition, the polarity of the data-arrayhas little meaning. In the present invention, two data-arrays areconsidered same if each bit in the first data-array and itscorresponding bit in the second data-array have the same or oppositevalues.

On the other hand, FIG. 10B discloses an x1x2 3-D stack 16 d of die 18d. In the first memory level 16C of the die 18 d, the data-coding layer6C for Bit-1 is printed from the data-mask region 8 b, while thedata-coding layer 6D for Bit-2 is printed from the data-mask region 8 a.Accordingly, for the die 18 d, p_(18d)[1,1]=−m(2), p_(18d)[1,2]=m(1).

For the dice 18 c and 18 d of FIGS. 10A-10B, their data-array sequencescan be expressed as:S _(18c)=(p _(18c)[1,1], p _(18c)[1,2])=(−m(1), m(2));S _(18d)=(p _(18d)[1,1], p _(18d)[1,2])=(−m(2), m(1));with {S_(18c)}={S_(18d)}, but S_(18c)≠S₁₈d.It can be observed that, the data-array set of the die 18 c is same asthat of the die 18 d, while the data-array sequence of the die 18 c is areverse of that of the die 18 d. For the same input address, thebit-order of the output needs to be reversed.

FIG. 12 is a circuit block diagram of a preferred 3D-oP 18. It comprisesan xMxn 3-D stack 16 and a configurable-I/O means 24. The 3-D stack 16comprises M×n data-arrays. Here, the data-array for the j-thbit-in-a-cell in the i-th memory level is denoted by p[i,j] (1≤i≤M,1≤j≤n). The configurable-I/O means 24 comprises a sequence-memory 22,which stores the information related to the data-array sequence of this3D-oP die. One example of the sequence-related information is chip ID.Chip ID is directly related to the location of the die on a wafer andcan be used to extract the information related to its data-arraysequence. The sequence-memory 22 is preferably an embedded non-volatilewritable memory. For example, it may use direct-write memory,laser-programmable fuse and/or electrically-programmable memory. For thedirect-write memory, the sequence-related information can be writtenduring manufacturing. For the laser-programmable fuse, thesequence-related information can be written during or aftermanufacturing. For the electrically-programmable memory, thesequence-related information can be written after manufacturing.

The configurable-I/O means 24, based on the sequence-relatedinformation, changes the input of the external I/O 28 and/or the outputof the internal I/O 26 in such a way that the external I/O 26 shows nodependence on the data-array sequence. In other words, all 3D-oPs in thesame batch, even though they might have different data-array sequence,appear to have the same external I/O 28 for users. More details on the3D-oP circuit are disclosed in FIGS. 13A-13B.

FIG. 13A is a circuit block diagram of the preferred x2x1 3D-oP 18 fromFIGS. 8A-8B. The input-address decoder 201 is shown in this figure. The3-D stack 16 stores two data-arrays p[1], p[2] for the memory levels16A, 16B, respectively. Here, the notation of data-arrays is simplifiedto p[i] (1≤i≤M) for the 1-bpc 3D-oP (i.e. each 3D-oP cell stores onebit). The input-address decoder 201 decodes the internal input address26. For example, if the most significant bit of the internal inputaddress 26 is ‘0’, the data-array p[1] is accessed; otherwise p[2] isaccessed. The configurable-I/O means 24 changes the value of theexternal input address 28 based on the sequence-related information: forthe die 18 a, the internal input address 26 is same as the externalinput address 28; for the die 18 b, the most significant bit of theinternal input address 26 is inverted from that of the external inputaddress 28.

FIG. 13B is a circuit block diagram of the preferred x1x2 3D-oP 18 fromFIGS. 10A-10B. The output buffer 200 is shown in this figure. The 3-Dstack 16 stores two data-arrays p[1,1] and p[1,2] for Bit-1 and Bit-2.The output buffer 200 comprises a plurality of output-groups 21, 21′ . .. . Each output-group stores outputs from all bits in a 3D-oP cell. Forexample, the output-group 21 comprises output-bits 21 a, 21 b, with theoutput-bit 21 a storing Bit-1 and the output-bit 21 b storing Bit-2,where Bit-1 and Bit-2 are from a same 3D-oP cell. The configurable-I/Omeans 24 changes the bit-order within each output-group 21 in the outputbuffer 200 based on the sequence-related information: for the die 18 c,the external output 28 is same as the internal output 26; for the die 18d, the bit-order within each output-group (e.g. 21) is reversed.

The technique of offset-printing to different memory levels (FIGS.8A-8B) can be combined with the technique of offset-printing todifferent bits-in-a-cell (FIGS. 10A-10B). To be more specific, themask-patterns for different memory levels and different bits-in-a-cellare merged onto a multi-region data-mask. At different printing steps,the wafer is offset by different values with respect to the multi-regiondata-mask. Accordingly, various data-patterns from the same data-maskare printed into data-coding layers for different memory levels anddifferent bits-in-a-cell. FIG. 14 illustrates an example. This preferredx2x2 3D-oP 18 e comprises two memory levels 16A, 16B with 2-bpc: Bit-1,Bit-2. There are a total of four data-coding layers. Their data-arraysare: p[1,1] for Bit-1 in memory level 16A; p[1,2] for Bit-2 in memorylevel 16A; p[2,1] for Bit-1 in memory level 16B; and p[2,2] for Bit-2 inmemory level 16B.

The left side of FIG. 15 illustrates the multi-region data-mask 8 usedfor the preferred x2x2 3D-oP 18. It comprises four data-mask regionswhose mask data-arrays are m(1)-m(4). The origin of the multi-regiondata-mask is O_(M). The right side of FIG. 15 illustrates all diceD[1]-D[4] in an exposure field Eon a 3D-oP wafer 9. Their origins areO₁-O₄, respectively. Because these dice D[1]-D[4] are offset-printedwith the same data-mask 8, they belong to the same 3D-oP batch.

FIG. 16 is a table listing the data-array for each data-coding layer ofeach die after each printing step for the preferred 2x2 3D-oP 18. Itsthird column lists the origin of the die to which O_(M) is aligned ateach printing step. Four printing steps are required for fourdata-coding layers. At the 1^(st) printing step (i.e. for p[1,1]), O_(M)is aligned to the origin O₁ of the die D[1] and the data-arrays p[1,1]of dice D[1]-D[4] are equal to m(1)-m(4), respectively. At the 2^(nd)printing step (i.e. for p[1,2]), O_(M) is aligned to the origin O₂ ofthe die D[2]. As long as the stepping distance D_(y) along the ydirection is twice as much as the die displacement d_(y) between D[2]and D[1], i.e. D_(y)=2d_(y), the data-arrays p[1 ,2] of dice D[1]-D[4]are equal to m(2), m(1), m(4), m(3), respectively. At the 3^(rd)printing step (i.e. for p[2,1]), O_(M) is aligned to the origin O₃ ofthe die D[3]. As long as the stepping distance D_(x) along the xdirection is twice as much as the die displacement d_(x) between D[3]and D[1], i.e. D_(x)=2d_(x), the data-arrays p[2,1] of dice D[1]-D[4]are equal to m(3), m(4), m(1), m(2), respectively. At the 4^(th)printing step (i.e. for p[2,2]), O_(M) is aligned to the origin O₄ ofthe die D[4]. As long as D_(y)=2 d_(y) and D_(x)=2 d_(x), thedata-arrays p[2,2] of dice D[1]-D[4] are equal to m(4), m(3), m(2),m(1), respectively.

In sum, for the dice D[1]-D[4] of FIG. 15, their data-array sequencescan be expressed as:S _(D[1])=(p _(D[1])[1,1], p _(D[1])[1,2], p _(D[1])[2,1], p_(D[1])[2,2])=(m(1), m(2), m(3), m(4));S _(D[2])=(p _(D[2])[1,1], p _(D[2])[1,2], p _(D[2])[2,1], p_(D[2])[2,2])=(m(2), m(1), m(4), m(3));S _(D[3])=(p _(D[3])[1,1], p _(D[3])[1,2], p _(D[3])[2,1], p_(D[3])[2,2])=(m(3), m(4), m(1), m(2));S _(D[4])=(p _(D[4])[1,1], p _(D[4])[1,2], p _(D[4])[2,1], p_(D[4])[2,2])=(m(4), m(3), m(2), m(1));with {S_(D[1])}={S_(D[2])}={S_(D[3])}={S_(D[4])}, butS_(D[1])≠S_(D[2])≠S_(D[3])≠S_(D[4]).From these expressions, it can be observed that all 3D-oP dice D[1]-D[4]have the same data-array set, but can have different data-arraysequences.

FIG. 17 is a circuit block diagram of the preferred x2x2 3D-oP 18. Theinput-address decoder 201 and output buffer 20O are both shown in thisfigure. They have the same functions are those of FIGS. 13A-13B. The 3-Dstack 16 stores four data-arrays p[1,1]-p[2,2]. The configurable-I/Omeans 24 changes the value of the external input address 28 and/or theinternal output 26 based on the sequence-related information: for thedie D[1], no change is made; for the die D[2], the bit-order within eachoutput-group (e.g. 21) in the output buffer 20O is reversed; for the dieD[3], the most significant bit of the internal input address 26 isinverted from that of the external input address 28; for the die D[4],the most significant bit of the internal input address 26 is invertedfrom that of the external input address 28, and the bit-order withineach output-group (e.g. 21) in the output buffer 20O is reversed.

The technique of offset-printing can not only be applied to thedata-coding layers in a single die, but also be applied to thedata-coding layers in a group of dice. Accordingly, the presentinvention discloses a three-dimensional 3D-oP-based memory package(3D²-oP). The 3D²-oP package is often released in the form of a memorycard. Similarly, the mask-patterns for a plurality of memorylevels/bits-in-a-cell of a plurality of dice are merged onto amulti-region data-mask. At different printing steps, the wafer is offsetby different values with respect to the data-mask. Accordingly, variousdata-patterns from the same data-mask are printed into data-codinglayers for different memory levels/bits-in-a-cell of different dice inthe 3D²-oP package.

FIG. 18 illustrates a preferred x3x3x1 3D²-oP package 38. Here, xKxMxn3D²-oP package denotes a memory package comprising K vertically stackedxMxn 3D-oP dice. In this example, it comprises three 3D-oP dice C₁-C₃.They are vertically stacked on an interposer substrate 30 and form a3D-oP stack 36. Bond wires 32 connect dice C₁-C₃ to the substrate 30. Toimprove its data-security, the 3D²-oP package 38 is preferably filledwith a molding compound 34.

FIG. 19 is a circuit block diagram of the preferred 3D²-oP package 38.Its 3D-oP stack 36 stores nine data-arrays, i.e. three data-arraysp[1]-p[3] for each of the dice C₁-C₃. It also comprises aconfigurable-I/O means 24, which has a similar function as that of FIG.17. The configurable-I/O means 24 could be located in the 3D-oP dieand/or the controller die.

The left side of FIG. 20 illustrates the multi-region data-mask 8 usedfor the preferred 3D²-oP package 38. It comprises nine data-mask regionswhose data-arrays are m(1)-m(9). The origin of the multi-regiondata-mask 8 is O_(M). The right side of FIG. 20 illustrates all diceD[1]-D[9] in an exposure field E on a 3D-oP wafer 9. The origins fordice D[1]-D[3] are O₁-O₃, respectively.

FIG. 21 is a table listing the data-array for each data-coding layer ofeach dice after each printing step for the preferred 3D²-oP package 38.Its third column lists the origin of the die to which O_(M) is alignedat each printing step. Three printing steps are required for threedata-coding layers. At the 1^(st) printing step (i.e. for p[1]), O_(M)is aligned to the origin O₁ of the die D[1] and the data-arrays p[1] ofdice D[1]-D[9] are equal to m(1)-m(9), respectively. At the 2^(nd)printing step (i.e. for p[2]), O_(M) is aligned to the origin O₂ of thedie D[2]. As long as D_(y)=3 d_(y1)=3 d_(y2), the data-arrays p[2] ofdice D[1]-D[9] are equal to m(3), m(1), m(2), m(6), m(4), m(5), m(9),m(7), m(8), respectively. At the 3^(rd) printing step (i.e. for p[3]),O_(M) is aligned to the origin O₃ of the die D[3]. As long as D_(y)=3d_(y1)=3 d_(y2), the data-arrays p[3] of dice D[1]-D[9] are equal tom(2), m(3), m(1), m(5), m(6), m(4), m(8), m(9), m(7), respectively.

FIG. 22 is a table listing three 3D²-oP packages M[1]-M[3] formed fromnine dice D[1]-D[9] of FIG. 20: the 3D²-oP package M[1] comprises diceD[1], D[4], D[7]; the 3D²-oP package M[2] comprises dice D[2], D[5],D[8]; and the 3D²-oP package M[3] comprises dice D[3], D[6], D[9].Because these packages M[1]-M[3] are offset-printed with the samedata-mask 8, they belong to the same 3D²-oP batch.

In sum, for the 3D²-oP packages M[1]-M[3] of FIG. 20, their data-arraysequences can be expressed as:S _(M[1])=(S _(D[1]) , S _(D[4]) , S _(D[7]))=(m(1), m(3), m(2); m(4),m(6), m(5); m(7), m(9), m(8));S _(M[2])=(S _(D[2]) , S _(D[5]) , S _(D[8]))=(m(2), m(1), m(3); m(5),m(4), m(6); m(8), m(7), m(9));S _(M[3])=(S _(D[3]) , S _(D[6]) , S _(D[9]))=(m(3), m(1), m(1); m(6),m(5), m(4); m(9), m(8), m(7));with {S_(M[1])}={S_(M[2])}={S_(M[3])}, but S_(M[1])≠S_(M[2])≠S_(M[3]).From these expressions, it can be observed that all 3D²-oP packagesM[1]-M[3] have the same data-array set, but can have differentdata-array sequences.

While illustrative embodiments have been shown and described, it wouldbe apparent to those skilled in the art that many more modificationsthan that have been mentioned above are possible without departing fromthe inventive concepts set forth therein. For example, besidesphoto-lithography, offset-printing can be applied toimprint-lithography. The invention, therefore, is not to be limitedexcept in the spirit of the appended claims.

What is claimed is:
 1. An offset-printing method for a three-dimensionalprinted memory with multiple bits-per-cell, comprising the steps of: 1)forming a substrate circuit on a semiconductor wafer, wherein said wafercomprises at least two adjacent dice including a first die and a seconddie; 2) a first printing step for transferring a first mask pattern of adata-mask to a first data-coding layer, wherein an origin of saiddata-mask is initially aligned to an origin of said first die at saidfirst printing step; 3) a second printing step for transferring a secondmask pattern of said data-mask to a second data-coding layer above saidfirst data-coding layer, wherein said origin of said data-mask isinitially aligned to an origin of said second die at said secondprinting step; wherein said first and second mask patterns are locatedon a same data-mask; said first and second data-coding layers are formedin a same memory level.
 2. The method according to claim 1, wherein saiddata-mask comprises at least first and second mask-regions whose maskpatterns are transferred to said first and second data-coding layers. 3.The method according to claim 2, wherein the mask pattern of said firstmask-region is transferred to said first data-coding layer in said firstdie at said first printing step.
 4. The method according to claim 2,wherein the mask pattern of said second mask-region is transferred tosaid first data-coding layer in said second die at said first printingstep.
 5. The method according to claim 2, wherein the mask pattern ofsaid first mask-region is transferred to said second data-coding layerin said second die at said second printing step.
 6. The method accordingto claim 2, wherein the mask pattern of said second mask-region istransferred to said second data-coding layer in said first die at saidsecond printing step.
 7. The method according to claim 2, wherein saidfirst data-coding layer of said first die stores a first data-array. 8.The method according to claim 2, wherein said second data-coding layerof said first die stores a second data-array.
 9. The method according toclaim 2, wherein said first data-coding layer of said second die storesa second data-array.
 10. The method according to claim 2, wherein saidsecond data-coding layer of said second die stores a first data-array.11. The method according to claim 1, wherein a displacement between saidfirst and second dice is smaller than a stepping distance of said firstprinting step.
 12. The method according to claim 11, wherein saidstepping distance of said first printing step is at least twice saiddisplacement between said first and second dice.
 13. The methodaccording to claim 1, wherein a displacement between said first andsecond dice is smaller than a stepping distance of said second printingstep.
 14. The method according to claim 13, wherein a stepping distanceof said second printing step is at least twice said displacement betweensaid first and second dice.
 15. The method according to claim 1, whereina total number of data-masks is fewer than a total number of data-codinglayers.
 16. The method according to claim 15, wherein said total numberof data-masks is one.
 17. The method according to claim 1, wherein saidfirst printing step is photo-lithography.
 18. The method according toclaim 1, wherein said second printing step is photo-lithography.
 19. Themethod according to claim 1, wherein said first printing step isimprint-lithography.
 20. The method according to claim 1, wherein saidsecond printing step is imprint-lithography.